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Abstract:

The present invention provides a low viscosity, aqueous concentrate
comprising a primary amine salt of glyphosate and surfactant. The aqueous
concentrate can be formed from a highly concentrated glyphosate
composition that has very low levels of glyphosate in non-salt form.
Exemplary aqueous concentrates include a primary amine salt of glyphosate
in the range of 45 percent weight to 68 percent weight, and a surfactant
at a concentration in the range of 3 percent weight to 27 percent weight,
with the concentrate having a viscosity in the range of 40 to 450
centistokes.

Claims:

1. A surfactant-containing aqueous glyphosate salt concentrate comprising
a primary amine salt of glyphosate at a concentration in the range of 45
percent weight to 68 percent weight, and a surfactant at a concentration
in the range of 3 percent weight to 27 percent weight, wherein the
concentrate has a viscosity in the range of 40 to 450 centistokes.

2. The surfactant-containing aqueous glyphosate salt concentrate of claim
1 wherein the primary amine salt of glyphosate salt is at a concentration
in the range of 50 percent weight to 68 percent weight.

3. The surfactant-containing aqueous glyphosate salt concentrate of claim
2 wherein the primary amine salt of glyphosate salt is at a concentration
in the range of 60 percent weight to 67 percent weight.

4. The surfactant-containing aqueous glyphosate salt concentrate of claim
1 wherein the surfactant is at a concentration in the range of 3 percent
weight to 7 percent weight.

5. The surfactant-containing aqueous glyphosate salt concentrate of claim
4 wherein the surfactant is at a concentration in the range of 4 percent
weight to 6 percent weight.

6. The surfactant-containing aqueous glyphosate salt concentrate of claim
1 having a viscosity in the range of 150 to 300 centistokes.

12. A method for preparing a surfactant-containing, aqueous glyphosate
salt concentrate comprising steps of:(a) providing a glyphosate acid
preparation comprising glyphosate acid, and a having water content of 35
percent weight or less;(b) providing a primary amine preparation
comprising a primary amine at 70 percent weight or greater;(c) combining
water with the glyphosate acid preparation to provide a glyphosate acid
slurry, wherein the amount of water combined is in the range of 25% to
35% of a total amount of material from the glyphosate acid preparation
and primary amine preparation added in step (d);(d) adding the primary
amine preparation to the glyphosate acid slurry, wherein the primary
amine reacts with the glyphosate acid to form a primary amine salt of
glyphosate, thereby producing a high-strength glyphosate salt aqueous
concentrate; and(e) combining a surfactant composition with the
high-strength glyphosate salt aqueous concentrate to form a
surfactant-containing, aqueous glyphosate salt concentrate, wherein
surfactant is present in the surfactant composition in an amount of
greater than 50 percent weight.

13. The method of claim 12 wherein the glyphosate acid preparation has a
water content of 5 percent weight or less.

15. The method of claim 12, wherein the surfactant is present in the
surfactant composition in an amount in the range of 70 to 100 percent
weight.

16. The method of claim 12, further comprising a step of adding additional
water to provide a high-strength glyphosate salt aqueous concentrate
comprising the primary amine salt of glyphosate in an amount in the range
of 63 percent weight to 70 percent weight, wherein adding additional
water is performed between step (d) and (e).

17. The method of claim 12, wherein on completion of step (d), greater
than 90 percent of the glyphosate acid in the glyphosate acid slurry
reacts with the primary amine to form the primary amine salt of
glyphosate.

18. The method of claim 12, wherein the glyphosate acid preparation has a
water content of 2 percent weight or less.

19. The method of claim 12, wherein the primary amine is present in the
primary amine preparation at 99 percent weight or greater.

20. The method of claim 12, wherein step (c) the amount of water combined
is in the range of 27.5% to 32.5% of a total amount of material from the
glyphosate acid preparation and primary amine preparation combined in
step (d).

21. The method of claim 12, wherein step (d), primary amine is added to
the to the glyphosate acid slurry at a rate in the range of 2.1% to 3.2%
per minute.

22. The method of claim 12, wherein the high-strength glyphosate salt
aqueous concentrate temperature formed in step (d) is kept at a
temperature in the range of 90.degree. F. to below 140.degree. F.

23. The method of claim 12, wherein step (d), the primary amine
preparation is added to the glyphosate acid slurry to provide a weight
ratio of primary amine to glyphosate acid in the range of 0.27:1 to
0.33:1

24. The method of claim 12, further comprising a step of filtering the
high-strength glyphosate salt aqueous concentrate, wherein filtering is
performed is performed between step (d) and (e).

25. The method of claim 24, wherein the step of filtering comprises
removing particulates that are greater that 1 μm.

26. The method of claim 12, wherein the glyphosate acid preparation has
one or more of the following features: less than 1 percent weight
formaldehyde, less than 1 percent weight nitrosamines.

27. A method for preparing a surfactant-containing, aqueous glyphosate
salt concentrate comprising steps of:(a) providing a high-strength
glyphosate salt aqueous concentrate comprising a primary amine salt of
glyphosate in an amount of 63 percent weight or greater, wherein the
concentrate comprises less than 1 percent weight unreacted glyphosate
acid, or a high-strength glyphosate salt aqueous concentrate comprising a
primary amine salt of glyphosate in an amount of 63 percent weight or
greater, wherein the concentrate comprises less than 1 percent weight
glyphosate particulates of a size greater than 1 μm, and(b) combining
a surfactant composition with the high-strength glyphosate salt aqueous
concentrate to form a surfactant-containing, aqueous glyphosate salt
concentrate, wherein surfactant is present in the surfactant composition
in an amount of greater than 50 percent weight.

28. A method for preparing a herbicide application composition comprising
a step of diluting the surfactant-containing, aqueous glyphosate salt
concentrate of claim 1 with water.

29. A method for controlling vegetation comprising applying to plants in a
post emergent or pre-emergent manner an application composition prepared
according to claim 28.

Description:

[0002]Glyphosate (N-phosphonomethyl glycine) is a well-known,
non-selective herbicide that is commonly applied to control the growth of
plants in a post-emergent manner. Glyphosate exhibits its herbicidal
effects by inhibiting the shikimic acid pathway in plants. By inhibiting
the shikimic acid pathway, the synthesis of aromatic amino acids and
other secondary metabolites becomes obstructed. The obstruction disrupts
protein synthesis, which ultimately results in plant death.

[0003]Aqueous glyphosate salt formulations have been preferred from a
commercial standpoint. The acid form of glyphosate has a low solubility
in water and therefore glyphosate is typically in salt form in aqueous
compositions. In addition, glyphosate in salt form is significantly more
biologically effective than glyphosate acid. Various salt forms of
glyphosate, which can be used in aqueous compositions, have been
described in the art (see, for example, U.S. Pat. Nos. 3,799,758,
4,140,513, 4,315,765, 4,481,026, and 4,507,250). In particular, aqueous
compositions containing the monoisopropylamine (MIPA) salt of glyphosate
have wide commercial use.

[0004]Some aqueous glyphosate salt compositions are sold in the form of
concentrates. These concentrates are typically diluted prior to plant
treatment and often include activity-enhancing surfactants. Surfactants
can enhance herbicide function by performing one or more of the following
functions: increase herbicide solubility in water, act as a cosolvent for
the herbicide, reduce surface tension of spray droplets (which can result
in increased droplet retention on vegetation and spread on a leaf
surface), and solubilization of cuticular leaf waxes.

[0005]Herbicide compositions in concentrate form can provide many
advantages, such as in reduction in storage space, reduction in packaging
material (e.g., container material), and improvements in shipping and
handling efficiencies. Despite the advantages that liquid concentrates
offer, there are various technical challenges associated with their use.
For example, at high herbicide concentrations, and with the addition of
additional components such as surfactants, the viscosity of the liquid
concentrate can be very high. High viscosity can make the composition
very difficult to handle, and create problems such as with pumping and
measuring the composition. As such, high viscosity can present many
difficulties for the end user, typically one who prepares an application
composition from the liquid concentrate. Lower temperatures can also
increase the viscosity of the liquid concentrates, making use in colder
climates or colder months more difficult.

[0006]The presence of surfactants can also present technical challenges in
liquid concentrates. For example, it is known that some surfactants can
reduce efficacy of glyphosate salt by interacting with it. It is also
known that surfactants can increase the viscosity of the herbicidal
formulation, further adding to the difficulties of high viscosities
associated with high concentration liquid formulations.

[0007]Yet another technical challenge relates to the physical stability of
the composition, as well as the herbicide active that is contained
therein. Storage of concentrate compositions at low temperatures can
result in the precipitation, crystallization, or sedimentation of the
herbicide active and/or secondary components, such as surfactants, out of
the composition. Storage of concentrate compositions at high temperatures
can result in the phase separation of components of the composition.
These types of changes are generally undesirable as they can render the
liquid concentrate composition unusable, or may require one or more
corrective processing steps to return the liquid concentrate to a usable
form.

[0008]According to estimates from the U.S. Environmental Protection
Agency, global herbicide use was approximately 2.0 billion pounds in 2000
and 2001. In the U.S., for combined agricultural and home applications,
glyphosate was the most used herbicide in 2001. Improvements in
glyphosate technology, particularly ones that allow for reductions in
material handling, mixing, packaging, and freight, can have a significant
impact on the carbon footprint associated with glyphosate use.

[0009]The current invention provides methods and compositions that not
only offer technical advantages associated with glyphosate use, but that
also are more environmentally friendly and economical.

SUMMARY OF THE INVENTION

[0010]Generally, the invention is directed to a surfactant-containing
glyphosate salt aqueous concentrate (also herein "aqueous concentrate").
The aqueous concentrate comprises a primary amine salt of glyphosate and
a surfactant. Although the glyphosate salt is present at a very high
concentration in the aqueous concentrate, it displays very good viscosity
and storage stability properties.

[0011]The invention also provides methods for preparing the aqueous
concentrate, methods for preparing herbicide application compositions
from the aqueous concentrate, application compositions made from the
aqueous concentrate, and methods for controlling plant growth using the
application compositions.

[0012]In one aspect, the invention provides a surfactant-containing
glyphosate salt aqueous concentrate that is storage-stable and that has a
low viscosity. The aqueous concentrate comprises a primary amine salt of
glyphosate and a surfactant. The concentration of the primary amine salt
of glyphosate is in the range of 45 percent weight to 68 percent weight
in the aqueous concentrate. The concentration of the surfactant in the
aqueous concentrate is in the range of 3 percent weight to 27 percent
weight. The aqueous concentrate also has a viscosity in the range of 40
to 450 centistokes (cSt).

[0013]An exemplary glyphosate salt for use in the aqueous concentrate is
glyphosate-monoisopropylammonium (glyphosate-MIPA). Also, an exemplary
surfactant for use in the composition is an alkoxylated alkyl amine
surfactant.

[0014]The invention also provides methods for forming the
surfactant-containing glyphosate salt aqueous concentrate. In one mode of
practice, the aqueous concentrate is formed using a high strength aqueous
glyphosate salt concentrate (also herein "high strength concentrate").
The high strength concentrate has a very high concentration of the
glyphosate salt, with low levels of microparticulates, and/or unreacted
glyphosate acid. The properties of the high strength concentrate carry
over to provide benefits to the aqueous concentrate.

[0015]The invention also provides methods for preparing
surfactant-containing glyphosate salt aqueous concentrates. Generally, to
form the aqueous concentrate, a surfactant composition containing a
minimal amount of water, or no water, is combined with a high strength
concentrate. The methods provide surfactant-containing aqueous
concentrates having a high concentration of the glyphosate salt, and very
good viscosity. The method and surfactant-containing concentrates of the
prior art provide improvements over surfactant-containing glyphosate salt
concentrates of the prior art. The concentrates of the current invention,
in addition to having commercially acceptable viscosity, can be diluted
to provide application compositions having amounts of glyphosate and
surfactant sufficient to achieve weed control. The present invention
overcomes difficulties in providing a concentrate having a high
concentration of glyphosate salt (e.g., above 41 percent weight) and an
amount of surfactant useful for achieving weed control when the
concentrate is diluted to an application composition. The invention
achieves this without increasing the viscosity of the concentrate to
commercially unacceptable levels.

[0016]In one aspect, the surfactant-containing glyphosate salt aqueous
concentrate is formed by a method including a step of providing a
glyphosate acid preparation having water content of 35 percent weight or
less, or preferably 5 percent weight or less. Also, a primary amine
preparation is provided comprising primary amine in amount of 70 percent
weight or greater, or preferably 95 percent weight or greater. A step of
combining water with the glyphosate acid preparation to provide a
glyphosate acid slurry is then performed. The amount of water combined is
in the range of 25% to 35% of a total amount of material from the
glyphosate acid preparation and primary amine preparation used to form a
high-strength glyphosate salt aqueous concentrate. Next, a step of adding
the primary amine preparation to the glyphosate acid slurry to create a
reaction mixture is performed. In the reaction mixture the primary amine
reacts with the glyphosate acid to form a primary amine salt of
glyphosate, thereby producing a high-strength glyphosate salt aqueous
concentrate. After this, a surfactant composition is combined with the
high-strength glyphosate salt aqueous concentrate to form a
surfactant-containing, aqueous glyphosate salt concentrate, wherein
surfactant is present in the surfactant composition in an amount of
greater than 50 percent weight.

[0017]In another aspect, the surfactant-containing glyphosate salt aqueous
concentrates is formed by a method including a step of providing a
high-strength glyphosate salt aqueous concentrate comprising a primary
amine salt of glyphosate in an amount of 63 percent weight or greater.
The high-strength glyphosate salt aqueous concentrate comprises less than
one percent weight unreacted glyphosate acid, and/or less than one
percent weight glyphosate particulates of a size greater than 1 μm.
After this, a surfactant composition is combined with the high-strength
glyphosate salt aqueous concentrate to form a surfactant-containing,
aqueous glyphosate salt concentrate, wherein surfactant is present in the
surfactant composition in an amount of greater than 50 percent weight.

[0018]The inventive aqueous concentrate provides various advantages for
the preparation, handling, and application of glyphosate herbicide
compositions. For example, with regards to shipping and handling, the
desirable viscosity allows the user to more easily measure and transfer
(e.g., by pumping) the aqueous concentrate. With regards to storage, the
improved stability affords the manufacturer, shipper, and user a greater
amount of time between the formulation of the aqueous concentrate, and
when it is actually used. Also afforded is more flexibility with regards
to storage conditions. With this in mind, overall, use of the inventive
aqueous concentrate provides a distinct economic advantage.

[0019]Because glyphosate salt can be present at a very high concentration
in the aqueous concentrate, the invention also provides advantages that
are reflected in one or more of the following reductions: material
handling, mixing, packaging, and freight. By providing any one or more of
these reductions, the carbon footprint associated with glyphosate use can
accordingly be reduced. The method and compositions of the invention are
therefore more environmentally friendly and economical.

[0020]Other aspects of the invention are related to methods for using the
aqueous concentrate to form herbicide application compositions. For
example, an application composition can be prepared by diluting the
aqueous concentrate with water. The invention also provides methods for
controlling the growth of vegetation comprising a step of applying the
herbicide application composition in a post-emergent or a pre-emergent
manner.

DETAILED DESCRIPTION

[0021]The embodiments of the present invention described herein are not
intended to be exhaustive or to limit the invention to the precise forms
disclosed in the following detailed description. Rather, the embodiments
are chosen and described so that others skilled in the art can appreciate
and understand the principles and practices of the present invention.

[0022]All publications and patents mentioned herein are hereby
incorporated by reference. The publications and patents disclosed herein
are provided solely for their disclosure. Nothing herein is to be
construed as an admission that the inventors are not entitled to antedate
any publication and/or patent, including any publication and/or patent
cited herein.

[0023]Generally, the invention provides a surfactant-containing glyphosate
salt aqueous concentrate ("aqueous concentrate"). The aqueous concentrate
includes a primary amine salt of glyphosate (such as glyphosate IPA) and
a surfactant. An exemplary aqueous concentrate comprises glyphosate-IPA
salt and an alkoxylated alkyl amine surfactant. The aqueous concentrate
displays good viscosity and good storage-stability.

[0024]In one mode of practice, the aqueous concentrate is prepared
starting with a high strength aqueous glyphosate salt concentrate ("high
strength concentrate"), which is a very highly concentrated glyphosate
salt aqueous composition. The high strength concentrate generally has
about 63 percent weight or greater, of a primary amine salt of glyphosate
in water. More specifically, the primary amine salt of glyphosate can be
at a concentration in the high strength concentrate of about 65 percent
weight or greater, or 67 percent weight or greater, such as about 68
percent weight. The high strength concentrate is typically in the form of
a clear, homogeneous salt solution. Typically, the high strength
concentrate does not include excipient component(s) (e.g., a surfactant)
in any appreciable amount(s).

[0026]In order to describe the surfactant-containing glyphosate salt
aqueous concentrate, the preparation of a high strength concentrate is
also discussed. As a general matter, high strength concentrates are
prepared by the combination of glyphosate acid with a primary amine
(base) in the presence of water. Glyphosate acid, which has a low
solubility in water, is converted to a highly soluble salt form upon
addition of the primary amine.

[0027]The terms "glyphosate acid" and "glyphosate", as used herein, refer
to fully protonated or deprotonated forms of the acid. Glyphosate acid
has the structure:

##STR00001##

(C3H8NO.sub.5P), a molecular weight of 169.1 Da, and the
chemical name N-(phosphonomethyl)glycine. Glyphosphate in acid form has a
very low solubility in water (about 12 g/L at 25° C.). On the
other hand, most salt forms of glyphosate are at least very soluble in
water. The acid dissociation constants for glyphosate are pKa1 0.8
(first phosphonic), pKa2 2.3 (carboxylate), pKa3 6.0 (second
phosphonic), and pKa4 11.0 (amine). In an aqueous solution,
glyphosate has a tendency to dissociate one proton from the phosphonic
acidic group and associate that proton with the amine group, forming a
dipolar molecule (zwitterion).

[0028]In one mode of practice, in order to prepare a high-strength aqueous
concentrate, a high purity, low water content glyphosate acid preparation
is provided. The glyphosate acid preparation can be a product of any
particular known synthetic processes for preparing glyphosate acid.
Various routes for the synthesis of glyphosate acid are known in the art.

[0029]One route, the "glycine route," involves the phosphonomethylation of
glycine. For example, cholormethyl-phosphonic acid can be reacted with
glycine in basic conditions. In another glycine route, dimethyl phosphate
is reacted with glycine to form glyphosate.

[0030]Another route is the catalytic oxidation of
N-(phosphonomethyl)iminodiacetic acid (PMIDA) (see, for example, U.S.
Pat. No. 3,954,848). The PMIDA route generally involves mixing PMIDA with
water and an acid (such as sulfuric acid), and then heating the mixture
to an elevated temperature. An oxidizing agent (such as an inorganic
peroxide, like hydrogen peroxide, or an organic peroxide) is then added,
which oxidatively converts iminodiacetic acid to glyphosate acid.
Oxidation can be performed in the presence of a noble metal catalyst such
as platinum, immobilized on a support. Precipitation of glyphosate acid
can be achieved by precipitation, using a water-miscible organic solvent.
Decomposition products observed using the PMIDA route can include
glyphosine, glycine, iminodiacetic acid, M-formylglyphosate, PMIDA,
(aminomethyl)phophonic acid (APMA), N-methyl-N-(phosphonomethyl glycine
(MePMG), and N-N bis(phosphonomethyl)amine (bPMNH).

[0031]Glyphosate can also be produced by the phosphonomethylation of
N-benzylglycine to N-benzyl glyphosate, followed by reaction with
hydrobromic or hydroiodic acid to cleave the benzyl group, which produces
glyphosate (see U.S. Pat. No. 3,956,370). Glyphosate can also be produced
by the phosphonomethylation of N-t-butyl glycine to form N-t-butyl
glyphosate, which is then converted to glyphosate via acid hydrolysis.
Processes using N-benzylglycine or N-t-butylglycine as starting materials
can produce byproducts such as isobutylene and toluene.

[0032]In some aspects the glyphosate acid preparation used to form the
high-strength aqueous concentrate has a water content of about 35 percent
weight or less, such as in the range of about 0.01 percent weight to
about 35 percent weight. Preferably, the glyphosate acid preparation has
a water content of about 5 percent weight or less. For example, in some
aspects, the glyphosate acid preparation used to prepare the
high-strength aqueous concentrate has a water content of about 4 percent
weight or less, about 3 percent weight or less, or about 2 percent weight
or less. For example, in some aspects the glyphosate acid preparation has
a water content in the range of about 0.01 percent weight to about 5
percent weight, or more specifically in the range of about 0.01 percent
weight to about 2 percent weight. The water content is the amount of
water by weight of all material (liquid and solid) present in the
glyphosate acid preparation. For example, in 100 g of a glyphosate acid
preparation having a water content of 5 percent weight, there is 95 g of
solids and 5 g of water.

[0033]The low water content significantly reduces the amount of
water-soluble impurities or liquid impurities that are associated with
the glyphosate acid preparation. For example, by using a glyphosate acid
preparation with a water content of 5 percent weight or less, impurities
such as formaldehyde and nitrosamines are substantially removed. For
example, in some aspects, the glyphosate acid preparation has less than 1
percent weight formaldehyde, and/or less than 1 percent weight
nitrosamines. (Examples of nitrosamine impurities include
N-nitrosodialkylamines, wherein the alkyl is methyl, ethyl, propyl, or
butyl, and N-nitrosopiperidine, N-nitrosopyrrolidine, and
N-nitrosomorpholine). Carbon is another impurity that may be associated
with the glyphosate acid preparation. These types of impurities are
though to nucleate formation of undesirable glyphosate acid particulates.
By removing these particulates, it significantly minimizes particulate
formation, which in turn results in a high-strength aqueous concentrate
with improved properties. These improved properties include good
viscosity and a high concentration of glyphosate in its biologically
effective form.

[0034]In some aspects, the glyphosate acid preparation used to form the
high-strength aqueous concentrate includes glyphosate acid at 98 percent
weight of total solids, or greater, or 99 percent weight of total solids,
or greater. For example, as a percentage of the solids in the
composition, the total non-glyphosate solids are present in the
glyphosate acid preparation used in an amount in the range of about 0.01
percent weight to about 2 percent weight, or more specifically in the
range of about 0.01 percent weight to about 1 percent weight.

[0035]Generally, a glyphosate acid preparation having a very low water
content (e.g., about 5 percent weight or less) is in the form of a dry
material (e.g., a dry flake or pellet), whereas a glyphosate acid
preparation having a higher water content (e.g., about 10 percent weight)
is in the form of a wet cake.

[0036]If desired, in order to lower the amount of moisture, the glyphosate
acid preparation can be subjected to a low-pressure environment, heat,
blown air, or combinations thereof. This can also be helpful in driving
off volatile impurities, such as formaldehyde and nitrosamines. A
low-pressure treatment can be performed prior to combining the glyphosate
acid with the primary amine salt.

[0037]A primary amine preparation is also used to form the high-strength
aqueous concentrate. A primary amine preparation refers to an amine base
of the general formula: H2NR, wherein R is a linear or branched
alkyl radical having 2-6 carbon atoms. Examples of primary amines useful
for forming a glyphosate primary amine salt in an aqueous concentrate
include monoisopropyl amine, mono-n-propylamine, and monobutylamine.

[0038]The primary amine preparation used to form the glyphosate salt of
the high-strength aqueous concentrate also has high purity. In the
primary amine preparation, any non-primary amine component(s) are present
in an amount of about 2 percent weight or less, or about 1 percent weight
or less.

[0039]In a preferred mode of practice, the primary amine base used to form
the glyphosate salt is monoisopropyl amine (MIPA, also IPA or
isopropylamine). Monoisopropylamine is a highly hygroscopic colorless
liquid that is miscible with water. In some aspects, the primary amine
preparation comprises MIPA at 70 percent weight or greater, such as in
the range of 70-99.9 percent weight. More preferably, the primary amine
preparation comprises MIPA at 95 percent weight or greater, such as in
the range of 95-99.9 percent weight.

[0040]For example, the primary amine preparation can have a water content
of about 2 percent weight or less, such as in the range of about 0.01
percent weight to about 2 percent weight, or about 0.01 percent weight to
about 1 percent weight. Accordingly, the amount of the primary amine in
the primary amine preparation is about 98 percent weight or greater, such
as in the range of about 98 percent weight to about 99.9 percent weight,
or about 99 percent weight to about 99.9 percent weight.

[0041]In the process of preparing the high-strength aqueous concentrate,
the glyphosate acid and the primary amine are reacted in a limited amount
of water. Preferably, purified water is used. Purified water for the
composition can come from, for example, a filtration process, a
deionization process, or a distillation process.

[0042]The method of preparing the high-strength aqueous concentrate
includes a step of combining water with the glyphosate acid preparation
to form a glyphosate acid slurry. After the slurry is formed, primary
amine is added to the slurry, which reacts with the glyphosate acid. The
amount of water that is combined to form the slurry can be described
relative to the total amount of glyphosate acid and primary amine used to
form the high-strength aqueous concentrate. In the step of forming the
slurry, an amount of water in the range of about 25% to about 35% of a
total amount of material from the glyphosate acid preparation and primary
amine preparation is combined with the glyphosate acid preparation. For
example, if 200 g of the glyphosate acid preparation and 60 g of primary
amine preparation is used to make the concentrate (260 g total material),
an amount of water from about 65 g up to about 91 g can be combined with
the glyphosate acid preparation to form the glyphosate acid slurry. In
more specific aspects, an amount of water in the range of about 27.5% to
about 32.5% of a total amount of material from the glyphosate acid
preparation and primary amine preparation is combined with the glyphosate
acid preparation.

[0043]The recited ranges of water can also take into account any
pre-existing water carried over from the starting glyphosate acid and/or
primary amine preparations. The greater the moisture content in the
glyphosate acid and/or primary amine preparations, the less water will be
needed to be combined with the glyphosate acid and primary amine
ingredients to form the high-strength aqueous concentrate.

[0044]In the step of combining, purified water can be combined with the
glyphosate acid preparation. Since glyphosate acid has a low solubility
in water, the addition of water can transform the glyphosate acid
preparation from a dry flake into an aqueous slurry, which generally is
in the form of a thick suspension of solids in a liquid. (After the
addition of the primary amine base, the slurry or suspension is
transformed into a clear concentrate by the reaction of the base with the
acid, and formation of the glyphosate salt.) If desired, mixing equipment
can be used to facilitate preparation of the slurry. During and/or after
combining the water the glyphosate acid, the slurry can be maintained at
a desired temperature. For example, the slurry is maintained at a
temperature of below about 120° C. (below about 49° C.).
Lower temperatures can be useful, since the next step of adding the
primary amine is understood to result in an exothermic reaction.

[0045]Next, a primary amine preparation is added to the glyphosate acid
slurry. The step of addition results in a "reaction mixture" of
glyphosate acid with the primary amine base, which results in the
formation of the primary amine salt of glyphosate in a high strength
aqueous concentrate. The reaction, in essence, transforms the low
solubility glyphosate acid into the highly soluble glyphosate salt, which
is solubilized by the water in the reaction mixture.

[0046]Typically, the addition of the primary amine is carried out using
mixing or some form of agitation to facilitate the rapid distribution and
reaction of the primary amine with the glyphosate acid in the mixture.
Mixing can also help ensure that the heat generated by the exothermic
reaction becomes more evenly distributed throughout the mixture.

[0047]During addition of the primary amine, the reaction mixture can be
treated so that it is maintained within a desired temperature range.
Typically, the reaction mixture is cooled since addition of primary amine
is understood to result in an exothermic reaction. In some aspects, the
reaction mixture is cooled to a temperature in the range of about
90° F. to below about 140° F. (about 32° C. to below
about 60° C.), in the range of about 90° F. to about
120° F. (about 32° C. to about 49° C.), or in the
range of about 105° F. to about 120° F. (about 40.5°
C. to about 49° C.).

[0048]The primary amine can be added to the glyphosate acid slurry at a
rate that drives reaction of the glyphosate acid with the primary amine
towards completion, and promotes complete or substantially complete
formation of the glyphosate salt. The rate of addition of the primary
amine can be chosen based on one or more factors, such as the
temperatures of the ingredients being combined, the batch size of the
high strength aqueous concentrate to be made, as well as the rate of any
mixing or agitation that is performed while the primary amine is added to
the slurry of glyphosate acid.

[0049]In some modes of practice, the primary amine is added to the slurry
of glyphosate acid at a rate in the range of about 2.1% to about 3.2% per
minute. Rate of addition of the primary amine can be calculated by the
amount of primary amine added to the glyphosate slurry per minute divided
by the total amount of primary amine and glyphosate acid used to make the
high strength aqueous concentrate. For example, if 100 kg of glyphosate
acid and 41.7 kg of primary amine are used to make the high strength
aqueous concentrate, and if primary amine is added to the glyphosate acid
slurry at 3.54 kg/min, the rate of addition is 2.5% per minute.

[0050]A preferred primary amine base is monoisopropyl amine (MIPA). MIPA
is in liquid form at temperatures lower than 32° C., and can, be
metered into the glyphosate acid slurry.

[0051]Generally, an amount of primary amine is added to the glyphosate
acid slurry to facilitate a high rate of reaction with the glyphosate
acid. In some aspects, the primary amine is added in a molar excess
relative to the glyphosate acid. For example, an amount of primary amine
can be added to provide a molar ratio of glyphosate acid to primary amine
in the range of about 1:1 to about 1:1.2, respectively. In the case of a
high-strength aqueous concentrate of glyphosate-IPA, glyphosate acid is
added in a mass amount of about three times that of IPA (i.e., a 3:1
weight ratio, such as 75 g of glyphosate acid and 25 g of IPA), which
falls within the molar range.

[0052]Generally, greater than 90 percent of the glyphosate acid in the
glyphosate acid slurry reacts with the primary amine to form the primary
amine salt of glyphosate.

[0053]After the primary amine is added, the reaction results in glyphosate
acid being converted into a glyphosate salt (for example,
glyphosate-IPA), wherein glyphosate salt is in soluble form in the
high-strength aqueous concentrate. At this point, the concentration of
glyphosate salt can be very high, such as about 75 percent weight or
greater, for example, between about 75 percent weight to about 80 percent
weight.

[0054]This high-strength aqueous concentrate can then be diluted with
water to provide a "second" high-strength aqueous concentrate that has a
glyphosate salt at a concentration commonly found in commercial use.
Surfactant does not have to be added at this point. For example, an
amount of water added can provide a second high-strength aqueous
concentrate with a glyphosate salt concentration in the range of 60
percent weight to about 75 percent weight, about 63 percent weight to
about 70 percent weight, about 65 percent weight to about 70 percent
weight, or about 67 percent weight to about 70 percent weight.

[0055]The high-strength aqueous concentrate (or more dilute second high
strength concentrate) can also be analyzed to determine properties such
as viscosity, quantity of unreacted glyphosate acid, the presence of
impurities, and the presence and quantity of particulates. In order to
determine the effectiveness of the method of forming the high strength
aqueous concentrate, analysis can be carried out before any optional
supplemental treatment of the high-strength aqueous concentrate (such as
filtration, which can further improve the quality of the high-strength
aqueous concentrate).

[0056]Because of the high purity of reagents used to form the
high-strength aqueous concentrate, the amount of unreacted glyphosate
acid and/or particulates is very low. If any unreacted glyphosate acid is
present, it typically is in the form of a glyphosate acid particulate,
which is considered a biologically ineffective component of a herbicide
composition.

[0057]The presence and amount of glyphosate acid particulates can be
determined using common techniques. For example, the presence of
particulates can be determined microscopically, or by using a flow
cytometer. The quantity of particulates can be determined using
centrifugation. For example, a sample of the high-strength aqueous
concentrate can be subjected to centrifugation to pellet glyphosate acid
particulates. Sedimentation centrifugation is a common technique for
removing particles of a selected size distribution from a suspension of
fine solids in liquids. The high-strength aqueous concentrate with
soluble glyphosate salt can be decanted, and then the pellet can be
weighed to determine the quantity of particulates relative to a volume of
high-strength aqueous concentrate, or relative to the amount of
glyphosate salt in the high-strength aqueous concentrate.

[0058]In some aspects, the method of the invention produces a
high-strength aqueous concentrate with an amount of particulates having a
size of about 1 μm or greater, in an amount of about one percent of
the weight, or less, of the glyphosate salt in the concentrate.

[0059]The pH of the high-strength aqueous concentrate can also be
determined using standard techniques. In some aspects, the high-strength
aqueous concentrate has a pH in the range of about 3 to about 6, or more
specifically in the range of about 4 to about 4.8.

[0060]The high-strength aqueous concentrate (or more dilute second
high-strength concentrate) can optionally be subjected to additional
treatment(s) to improve the quality of the concentrate. For example, the
high-strength aqueous concentrate can be subjected to one or more
filtration steps. The filtration steps can remove particulates that may
be present in the high-strength aqueous concentrate. Since the method of
the invention already results in a low particulate level (without
supplemental treatment) that, in turn, provides good viscosity, and makes
the high-strength aqueous concentrate is easier to filter.

[0061]One or more optional steps of filtration, in turn, can further
improve properties of the high-strength aqueous concentrate, such as by
further lowering its viscosity.

[0062]A filtration step can include the use of a coarse filter to remove
large particulates. Exemplary coarse filters have pore sizes in the range
of about 10 to 200 microns. Generally, a 10 micron filter will trap
particulates having a smallest dimension of about 10 microns or greater
on the filter, while allowing particles of smaller to flow through.
(Particulates have spherical and cubical shapes generally have their
largest dimension on the order of their smallest dimension, whereas the
smallest dimension of rod shaped particles corresponds to their width,
not length.)

[0063]A coarse filter can be used with vacuum filtration to pull the
high-strength aqueous concentrate through the filter and remove the
particulates. In some aspects, filtration is performed while the
high-strength aqueous concentrate is still very warm, for example at a
temperature in the range of about 95° F. to about 113° F.
(about 35° C. to about 45° C.).

[0064]Another treatment involves the use of a fine filter to remove
smaller particulates such as those that flow through the large filter.
For example, the high-strength aqueous concentrate (or more dilute second
high-strength concentrate) can be filtered through a fine filter having a
pore size of about 1 micron. A fine filter can be used in a single
filtration step of the high-strength aqueous concentrate, or can be used
to remove smaller particulates following coarse filtration. Fine
filtration can therefore further reduce the amount of particulates that
are present in the aqueous concentrate.

[0065]In some modes of practice filtration can be performed after addition
of surfactant. For example, the high strength concentrate is filtered
using a course filter, a surfactant is then added to prepare a
surfactant-containing aqueous concentrate, and then the
surfactant-containing aqueous concentrate is filtered using a fine
filter.

[0066]The high strength concentrate can be used for the formation of the
surfactant-containing glyphosate salt aqueous concentrate ("aqueous
concentrate"). In some modes of forming the aqueous concentrate, a
process is carried out so that a nominal amount of water is introduced
into the high strength concentrate along with surfactant. Minimizing the
amount of water introduced provides an aqueous concentrate where a higher
concentration of the primary amine glyphosate salt is maintained. To
accomplish aqueous concentrate formation, surfactant can be added in a
concentrated form.

[0067]A surfactant composition can also be added to the high strength
concentrate to form the aqueous concentrate. The surfactant composition
can include one or more surfactants. In some cases, the surfactant
composition can also include a diluent, such as water and/or one or more
other liquids. Exemplary non-water diluents for the surfactant
composition include diethylene glycol and propylene glycol. An exemplary
concentrated surfactant composition includes surfactant in an amount of
about 50 percent weight or greater in the composition, such as in the
range of about 70 percent weight to about 100 percent weight.

[0068]In other cases, surfactant is added in "neat" form, meaning that
there are at most trace amounts of non-surfactant material(s) present
along with surfactant. Surfactants can be in solid or liquid neat form.

[0069]A single surfactant type, or a combination of two or more different
surfactants can be used to form the aqueous concentrate. Generally, an
amount of surfactant is added to the high strength concentrate (or more
dilute second high-strength concentrate) so the concentration of the
glyphosate salt does not fall below about 45 percent weight. More
preferably, surfactant is added to the concentrated glyphosate salt
composition so the concentration of the glyphosate salt does not fall
below about 46 percent weight, below about 47 percent weight, below about
48 percent weight, below about 49 percent weight, below about 50 percent
weight, below about 51 percent weight, below about 52 percent weight,
below about 53 percent weight, below about 54 percent weight, below about
55 percent weight, or most preferably below about 56 percent weight.

[0070]Exemplary concentration ranges of the glyphosate salt in the aqueous
concentrate are from about 45 percent weight to about 68 percent weight,
from about 48 percent weight to about 68 percent weight, from about 50
percent weight to about 68 percent weight, from about 51 percent weight
to about 68 percent weight, from about 52 percent weight to about 68
percent weight, from about 53 percent weight to about 68 percent weight,
from about 54 percent weight to about 68 percent weight, or most
preferably from about 55 percent weight to about 67 percent weight.

[0071]Ranges of surfactant in the aqueous concentrate are from about 3
percent weight to about 27 percent weight, more preferably from 3 percent
weight to about 7 percent weight, and most preferably from about 4
percent weight to about 6 percent weight.

[0072]In more specific aspects, the concentration of primary amine salt of
glyphosate in the aqueous concentrate is in the range of about 55 percent
weight to about 67 percent weight and surfactant is in the range of about
4 percent weight to about 6 percent weight. An exemplary aqueous
concentrate includes about 58 percent weight of glyphosate IPA, and about
5 percent weight surfactant.

[0073]Accordingly, in aspects of the invention providing an aqueous
concentrate wherein the presence of non-glyphosate salt components and
non-surfactant components (other than water) are minimized, the invention
provides an aqueous concentrate consisting essentially of a primary amine
salt of glyphosate in an amount in the range of 45 percent weight to 66
percent weight, and a surfactant at a concentration in the range of 3
percent weight to 7 percent weight. In other words, in these aspects, the
aqueous concentrates do not include materials other than the primary
amine salt of glyphosate, surfactant, a minimal amount unreacted
glyphosate acid or glyphosate particulates, and water, in any substantial
amount.

[0074]In order to prepare the aqueous concentrate, surfactant can be
combined with the high-strength concentrate. The step of combining can be
performed at a desired temperature, typically in the range of about
0° C. to about 50° C., and more preferably after the high
strength concentrate has cooled to a temperature below about 35°
C., such as in the range of about 0° C. to below about 35°
C. Surfactant can be added to the high strength concentrate batch wise,
in a continuous manner (for example, with metering), or in a
semi-continuous manner. Active mixing (by stirring or agitation) can be
performed to facilitate formation of the mixing of the aqueous
concentrate. Surfactant can be combined with the high strength
concentrate in an appropriate mixing vessel, such as one that
accommodates the volume of aqueous concentrate to be made. The mixing
vessel can include features such as an agitator (e.g., paddle or
propeller type), a heating or cooling jacket, and baffles.

[0075]Types of surfactants that can be present in the aqueous concentrate
include cationic surfactants, anionic surfactants, non-ionic surfactants,
ionic surfactants, and amphoteric surfactants. Combinations of two or
more surfactants can be used to form the aqueous concentrate.

[0076]An exemplary aqueous concentrate is described with regards to an
alkoxylated alkyl amine surfactant. However, any known surfactant, or
combination of surfactants, can be combined with the high-strength (or
secondary high-strength) concentrate to form the aqueous concentrate.

[0077]Exemplary alkoxylated alkyl amine surfactants include those having
the formula R1NR2R3, wherein R1 includes a
hydrocarbon group having 8 or more carbon atoms, and R2 and R3
are independently selected from oxyalkylene polymeric chains. In some
aspects R1 is a C8-22 alkyl group. In some aspects R2 and
R3 are respectively represented by (R4--O)m--X and
(R4--O)n--X, wherein in R2 and R3, R4 is
independently C2-4 alkene, and m and n have a combined value in the
range of 2 to about 50.

[0078]Exemplary alkoxylated alkyl amine surfactants include
polyoxyalkylene derivatives of tallowamine, cocoamine, and oleoylamine.
In preferred aspects, the alkoxylated alkyl amine surfactant is
polyoxyalkylene tallow amine. In preferred aspects, the alkoxylated alkyl
amine surfactant has 2 to about 15 ethylene oxide groups (EO) per amine,
or from about 5 to about 10 EO groups per amine.

[0080]Another surfactant type that can be present in the aqueous
concentrate is a quaternary ammonium-based surfactant. Quaternary
ammonium surfactants include those with alkylation, ethoxylation, or
propoxylation, or combinations thereof. Exemplary quaternary ammonium
surfactants are commercially available under the trademarks Ethoquad®
and Arquad® (AkzoNobel, Chicago, Ill.), EMCOL® CC (Witco Chemical).
Quaternary ammonium glycoside surfactants are also described in JP
4-193891 and WO 99/10462.

[0081]Another surfactant type that can be present in the aqueous
concentrate is an alkyl glycoside, which including alkyl polyglucosides
(APGs). Alkyl glycosides include several commercial surfactants
collectively known in the art or referred to herein as "alkyl
polyglucosides" or "APGs". Exemplary alkyl glycosides are Agrimul®
PG-2069 (Henkel), Agrimul® PG-2076, and Eucarol® AGE.

[0082]Another surfactant type that can be present in the aqueous
concentrate is an alkoxylated phosphate ester, such ethoxylated phosphate
esters. Examples include phosphate esters of alkylphenoxy
polyethoxyethanol, and phosphate esters of alkylphenol ethoxylates.
Commercially available ethoxylated phosphate ester surfactants include
Stepfac® 8170 (Stepan Co., Northfield, Ill.) and Emphos® (Witco
Chemicals, of Brooklyn, N.Y.)

[0083]Another surfactant type that can be present in the aqueous
concentrate is an alkyldimethylamine. Examples include cocodimethylamine,
tallowdimethylamine, dodecyldimethylamine. Commercially available
alkyldimethylamines include Armeen® DM12D (AkzoNobel) as Noram® DMC
or DMS (Ceca) respectively.

[0084]Another surfactant type that can be used in the present in the
aqueous concentrate is a disulfonate surfactant. Examples of disulfonate
surfactants include salts of alkyl diphenyl ether disulfonates and salts
of alkyl diphenyl oxide disulfonates. Exemplary disulfonates include
Dowfax 3B2® (Dow Chemicals, Midland, Mich.) and Fenopon C0436® (GAF
Corp., New York, N.Y.).

[0085]Another surfactant type that can be used in the present in the
aqueous concentrate is a poloxamer (a polyalkylene derivative of
propylene glycol), such as Pluronic F68® (BASF, Parsippany, N.J.).

[0086]Other surfactant types that can be present in the aqueous
concentrate are alkylbetaines and alkyletherbetaines. A specific example
of an alkylbetaines is cocobetaine, available as Velvetex® AB-45
(Henkel) or Tego® Betaine F 50 (Goldschmidt).

[0087]The resulting aqueous concentrate has a good viscosity, which allows
the aqueous concentrate to be handled with greater ease.

[0088]The viscosity of the aqueous concentrate can be determined using
standard techniques. Test guidelines for viscosity measurement can be
carried out according to EPA guidelines 830.7100. Equipment for
determination of viscosity can include, for example, a Brookfield
Viscometer LVT, with a number 3 spindle. The speed setting knob can be
placed at 60/3, and the viscosity of the aqueous concentrate can be
measured at room temperature. In some aspects, the aqueous concentrate
has a viscosity in the range of about 50 centistokes (cSt) to about 450
cSt, about 100 cSt to about 375 cSt, about 150 cSt to about 300 cSt,
about 175 cSt to about 275 cSt, or about 200 cSt to about 250 cSt.

[0089]The aqueous concentrate also displays good storage stability. One
test of storage stability is to determine the temperature of phase
separation of the concentrate. Phase separation can be measured by cloud
point, which is the temperature at which phase separation of materials in
a herbicide composition occurs. As a general matter, for commercial
acceptability, herbicide concentrates have a cloud point of about
50° C. or greater. In some aspects, the aqueous concentrate does
not show signs of clouding at temperatures below about 60° C.

[0090]Optionally, excipients other than the surfactant can be included in
the aqueous concentrate. However, if included, they are desirably kept at
lower concentrations to allow for a very high concentration of the
glyphosate salt in the aqueous concentrate. Other optional excipients
that can be included in the composition include, but are not limited to
antifoam agents, compatibilizing agents, sequestering agents,
neutralizing agents and buffers, corrosion inhibitors, dyes, odorants,
penetration aids, wetting agents, spreading agents, dispersing agents,
thickening agents, freeze point depressants, antimicrobial agents, crop
oil, and the like. These optional excipients can alternatively be
introduced into an application composition when the aqueous concentrate
is diluted prior to use.

[0091]An "application composition" refers to a diluted form of the aqueous
concentrate which has a glyphosate salt concentration useful for
controlling the growth, or killing one or more desired plant species. To
provide an application composition, the aqueous concentrate can be
diluted with water to provide for a desired application concentration of
glyphosate salt. The application concentration of glyphosate salt can be
chosen by one or more factors, such as the type of vegetation to be
treated, the rate of application of the application composition, and the
use of one or more other excipients which may enhance the function of the
glyphosate salt, or improve properties of the application composition.

[0092]The application composition can then be applied to foliage of plants
to be killed or controlled. Spraying is a common method for applying the
application compositions to foliage. For application, the application
composition can be applied in any convenient volume of water. Typical
ranges are from about 50 L/ha to 1,000 L/ha. Common amounts of glyphosate
(a.e.) used in method for controlling plant growth are in the range of
about 0.1 to about 5 kg/ha, and more preferably about 0.5 to about 2
kg/ha.

[0094]Application compositions made from the aqueous concentrates of the
current invention provide improved biological activity compared to
application compositions prepared from aqueous glyphosate salt
concentrates known in the art. The improved biological activity of the
application compositions described herein is thought to result from a
greater concentration of the biologically effective glyphosate salt form,
which is carried over from the aqueous concentrate. In other words, as a
percentage of solid materials in an application composition, the
compositions of the invention (application compositions, as well as
aqueous concentrates and high strength concentrates) contain a high
percentage of biologically active glyphosate salt. As a result, the
aqueous concentrates of the invention are effective in forming
application composition with high biological activity for controlling the
growth of one or more plant species.

[0095]Generally, biological activity of an application composition can be
determined under controlled field conditions applying scientific methods
and processes as generally accepted by the Weed Science Society of
America. The biological activity of an application composition of the
current invention can be determined by treating plant species in a
standard field trial. Application compositions are standardized according
to the calculated acid form of the glyphosate (a.e.) in the composition,
are generally based on the glyphosate salt content (a.i.) of the aqueous
concentrate.

[0096]According to one mode of practice, a test for biological activity
can be performed using the following steps. First, an application
composition is prepared from an aqueous concentrate of the invention. The
application composition can have a concentration of glyphosate commonly
used for the control of plant growth. The application composition is then
applied to an area of ground having one or more or the following weed
types: kochia, ryegrass, sedge (cyperus), barnyard grass, sicklepod,
pigweed, foxtail, and/or in a post emergent manner. Alternatively, the
application composition is applied to an area of ground capable of
growing one or more or the following weed types: kochia, ryegrass, sedge
(cyperus), barnyard grass, sicklepod, pigweed; foxtail, and/or in a
pre-emergent manner. At day 0, the application composition is applied to
provide an amount of glyphosate (a.e.) of 0.454 kg per acre At day 21 the
area that is treated with the application composition is assessed to
determine the control over plant growth.

[0097]Using this method, the application compositions of the invention are
able to control the growth of one, or more, or all of the plant species
(kochia, ryegrass, sedge (cyperus), barnyard grass, sicklepod, pigweed,
and/or foxtail) by about 80% or greater, such as in the range of about
80% to about 100%. For example, using this method, the control of rye
grass growth is about 80% or greater, such as in the range of about 80%
to about 85%. As another example, the control of cyperus growth is about
90% or greater, such as in the range of about 90% to about 95%. As
another example, the control of barnyard grass growth is about 90% or
greater, such as in the range of about 90% to about 95%. As another
example, the control of pigweed growth is about 90% or greater, such as
in the range of about 90% to about 95%. As another example, the control
of sicklepod growth is about 92% or greater, such as in the range of
about 92% to about 98%. As another example, the control of kochia growth
is about 95% or greater, such as in the range of about 95% to about100%.
As another example, the control of foxtail growth is about 95% or
greater, such as in the range of about 95% to about 100%.

[0098]Generally, the application composition of the invention provides
visual ratings of 80% efficacy or greater, and are tested against
Duncan's New Multiple Range Test. Range values followed by the same
letter are generally considered not statistically different and hence not
scientifically different. Table 1 shows the control of growth of various
weed species using application compositions formed from commercially
available glyphosate-containing herbicide concentrates and from
concentrates of the current invention.

Example 1

[0099]Herbicide application compositions were prepared from aqueous
concentrates of the present invention, and also from commercially
available glyphosate concentrates. Helosate® formulations are aqueous
concentrates prepared according to the present invention. PowerMAX®
(Monsanto), Touchdown® (Syngenta), Glyfos Extra® (Cheminova), and
Credit Extra® (Nufarm Americas) were used to prepare application
compositions for comparative testing.

[0100]Table 1 shows comparison of application composition prepared from
various commercial concentrates products on various weed species. The
following weed species are abbreviated as follows: ECHCG (barnyard
grass), CASOB (sicklepod), AMAXX (pigweed), and SETXX (foxtail).
Application compositions were applied to plant species containing in an
application amount of 0.454 kg a.e. glyphosate/acre (1 lbs./acre; 1.125
kg/ha). The numbers to the right of the herbicide formulations represent
percentage control of the identified plant species at 7 and 21 day time
points.